Magnetotransport properties of nonstoichiometric Si-Mn alloys with an excess of manganese relative to silicides Mn4Si7 and MnSi

摘要

Comparative examination of magnetotransport properties of nonstoichiometric Si1-x Mn (x) alloys with roughly the same (delta N.../x ae 7%) excess of Mn relative to silicides Mn4Si7 and MnSi has been performed. Films of Si1-x Mn (x) (N... ae 0.39 and 0.535) with a thickness of 60-70 nm have been fabricated by means of pulsed laser deposition on Al2O3 (0001) substrates at a temperature of 340A degrees D. It has been found that the excess of Mn produces the strongest effect on the Curie temperature in the case of MnSi (D cent (D) increases from 30 K to 300 K and higher), while no such effect is observed in Mn4Si7. This may be attributed to strong nonmagnetic disorder in Si1-x Mn (x) with x ae 0.39 and the associated unusual behavior of negative magnetoresistance (NMR): The NMR varies linearly with magnetic field at D' ae 1.3 T and exhibits almost no temperature dependence at T = 40-85 K.